Southern California Edison, striving to win approval for restarting at least one crippled nuclear reactor at San Onofre, told the Nuclear Regulatory Commission (NRC) Monday that it could meet the agency’s requirement that it be able to run safely at “full power,” but would redefine “full power” to be 70%.

Edison’s response to Administrative Judge Gary Arnold’s question about whether it could run at 99% power was to assert that the “normal steady state full power” was 70% and that should be good enough. Running at real full power runs the risk of re-damaging tubes that leaked radioactive steam a year ago and led to the plant being shut down.

An investigation found that a $640 million retrofit by Mitsubishi resulted in hundreds of eroded steam tubes, damaged by excessive vibration. Mitsubishi blamed computer problems and bad math for the misdesigned equipment. Edison replaced a bunch of tubes and said running at lower power would reduce vibration and allow the plant to keep producing electricity.

The NRC is expected to make a decision on the plant’s future in March.

San Onofre supplied electricity to 1.4 million homes in Southern California before the breakdown. Critics say running the plant under current conditions would turn San Onofre into a giant science experiment, testing the limits of a faulty design structure. Some also allege that Edison and Mitsubishi knew of the design flaws but went ahead without notifying the NRC or the state, partially to avoid having to submit to a full license renewal process. Edison denies that.

Who is at fault, and for what, could come into play rather quickly as the bill comes due for the continued staffing and repairs at San Onofre, along with the cost of securing replacement energy. The price tag so far is $400 million through December. Shareholders, ratepayers, taxpayers, insurers and Mitsubishi all have a huge stake in the outcome.

The plant has come under increasing scrutiny, with California Senator Barbara Boxer and Massachusetts Congressman Ed Markey calling for an amped-up investigation by the NRC after they alleged that a report by Mitsubishi outlining problems with the steam tubes before they were installed was hushed up. The report has not yet been released.

Last week, Markey suggested in a letter to the Securities and Exchange Commission (SEC) that Edison should be investigated for possible violations of securities laws by not revealing the problems.

–Ken Broder

To Learn More:

Can 70 Pct be Full Power at San Onofre Nuke Plant? (by Michael R. Blood, Associated Press)

Cost for Troubled San Onofre Plant? $400 Million and Growing (by Abby Sewell, Los Angeles Times)

Regulator Wary of Edison Shortcut for Testing Crippled San Onofre Nuclear Plant (by Ken Broder, AllGov California)